Microbial community of commercially reared pig feces in China

Understanding the metal(loid)s contamination and microbiota composition of pig feces is an important step required to support the design and implementation of an effective pollution control and prevention strategy in China. In this study, a national-scale survey was implemented to investigate the metal(loid) content and the composition of the microbial community of commercially reared pigs during several growing periods, defined as the early fattening growth phase (denoted as the Q group) and the later fattening growth phase (denoted as the H group). These data showed that Al, Mn, Cu, Zn, and Fe pollution was common in pig feces and Zn in Q group feces was nearly two times higher than the levels measured in the H group. The composition of the microbial of the Q group exhibited more operational taxonomic unit (OTUs) richness, whilst having fewer bacteria associated with human diseases when compared with those of the H group. Spearman rank correlation analysis showed that Cu and northern latitudes demonstrated a significantly positive effect on the richness of pig feces bacterial communities. Zn and Cd exhibited the biggest impact depending on the age of the animal, on the fecal composition of the microbial community as revealed by canonical correspondence analysis (CCA). Functional metagenomic prediction indicated that about 0.8% genes of pig feces bacteria community were related to human diseases. Similarly, the H group had significantly more pathogenic genes than those of Q group. These results pointed to the need to monitor heavy metal contamination of the pig production chain, particularly at earlier fattening stages, while controlling for pathogens of importance to human health, at latter stages of the growing cycle.